pacoflyer

My Feedback: (23)

I just recently set up new plane using 2 Hitec 7955s on the rudder. The rudder in all positions ,neutral and deflected, jitters like crazy with the motor NOT running. I've switched out the DX 7 receiver for a new one and the problem continues. All digital servos have some jitter to them but I've never seen this happen throughout the entire range of deflection and at rest, in neutral. Battery strength is good as are all the connections The sevo wires going back to the tail are long on this 36% plane but I didn't think that would be an issue. What am I doing wrong?
Thanks

A.T.

A little more information please:
Were the servos bench tested (direct to RX) and centered AOK before installation?
Are the servo extension leads twistedheavy duty, at least22 guage?
Battery chemistry and capacity? Voltage?
Are regulators, if fitted, able to handle the current requirements of high torquedigital servos?.

regards
Alan T.

pacoflyer

My Feedback: (23)

Alan,
Thanx for your reply..
The servos are new and worked fine with a Futaba 2.4 FAST receiver.
I do have heavy gauge twisted wire wire throughout. I have two regulators with two Fromeco Li on 2400 Mah batteries at 7.4 v.

Best,
paul

Brendan Lugo

First thought says it's probably your regulators not allowing enough amperage. Figure atleast 2 amps per servo when choosing a regulator. If the remainder of your equipment can also handle the 7.4 volts from the battery then I would get rid of the regulators all together. The 7955's can handle that voltage.

pacoflyer

My Feedback: (23)

Thanks Brendan,
I beleive the Fromeco Ariziona regulators are set for 6 v. Maybe that's not enough. If I can get my hands on a Hitec programer, would re-programing the jittering servos maybe solve my problem ? I've got 5945s [2ea] on each aileron and also on the the elevators. Can I get rid of the regulators if the re-programing does not work ?
paul

mglavin

My Feedback: (31)

Does the jitter stop if you remove the control horn from the servo? Is the rudder hard link connected or cables?

pacoflyer

My Feedback: (23)

Thanks Mike for your reply...
The rudder is on a pull pull and the jitter does reduce a little when you remove the horns from the servos. This may be due to the fact that I have changed the deadband using one of your programers to 8 on each of the two sevos. We're gonna keep playing with the linkage to see if we can tweek it some more. Another thought was to switch out the DS 7 and install a Hitec Aurora and see if that works better. When the Futabab 2.4 was in there, the servos performed perfectly...

Thanks agian,
paul

mglavin

My Feedback: (31)

Paul

It’s very important to match the servos center and travel end-points in this circumstance. And yes opening the dead-band may calm things down a bit. I strongly suggest the use of an inline servo amp-meter to set-up travel volumes and match centers. This inexpensive tool is invaluable IMO, Hangar 9 offers these, I have three which I use simultaneously when setting up multi servo surfaces. And of course the Hitec Programmer is must have too for best results!

pacoflyer

My Feedback: (23)

Michael, Thanks for info on the inline amp meter. I plan to use your programer to return all servos to factory settings and see what that does. The only problem is ..that may close the dead band and worsen my problem. If all else fails is there any reason to send back the sevos to Hitec and have them checked out ?

mglavin

My Feedback: (31)

Its unlikely returning the servos to factory defaults will solve any problems. Servos used in ganged applications must be match centered and provide equal degrees of rotation stop to stop. Best case to start with is to use a Servo jig rig as Brendon noted above, subsequently when installed in the model use the inline ammeters to monitor the current draw at center and travel extremes and reprogram or tweak the linkage to minimize current draws.

pacoflyer

My Feedback: (23)

Will do
Thansk very much